Anatomy & Organs

Chromosomes – structure, function & diseases


Chromosomes are the transmitters of genetic information. They ensure that the physical characteristics of the parents are passed on to their common children. At the same time, serious diseases can develop if the chromosomes are disturbed.

What are chromosomes?

DNA is the basis for heredity. This is coiled up in the form of chromosomes . Humans have 46 chromosomes. Of these, 23 are from the mother and 23 from the father. Except for germ cells , every cell in the human body has 46 chromosomes.

The number of chromosomes differs from species to species, but does not provide any information about the development of the organism. For example, blackbirds have 80 chromosomes. The chromosomes occur in homologous pairs.

This means that two chromosomes are responsible for reproducing genetic information. Of the 46 chromosomes, two are called gonosomes. Your job is to determine the gender. The chromosomes are located in the cell nuclei, which are also referred to as carriers of the genetic material.

If you unrolled its structure, it would measure a length of about 2 meters. During cell division, the chromosomes also divide. This process is called mitosis or meiosis. Meiosis takes place in the germ cells, egg cell and sperm , mitosis in all other body cells. The existing chromosomes are reproduced in such a way that they are always identical.

Anatomy & Structure

Chromosomes are made up of two halves. These are often not of equal length and are called chromatids. The halves interlock in the middle. Chromosomes that join at either end of the chromoatid are called submetacentric. The arms appear shortened. The place where the halves join is called the centromere.

During mitosis or meisoe, the chromatids divide at the centromere and are pulled to the cell ends. Since every cell carries genetic information, it is necessary for this to also be duplicated during cell division. The chromatids are made up of coiled DNA. This in turn is staggered into a double strand.

Two pairs of bases are joined together in the double strand. These face each other and are complementary. Only two of the four different base pairs ever match. The arms of the chromosome are usually in a position that looks like an X.

Function & Tasks

Chromosomes have two special tasks: on the one hand they determine the sex of the child, on the other hand they provide all the necessary genetic information. These include, for example, the color of eyes and hair. The inherited information comes from mother and father. That is why the chromosomes always appear in pairs. The traits are inherited in a dominant or recessive manner.

Since the same characteristic is passed on by mother and father and thus, for example, the information for two different eye colors would be available, one of the characteristics must assert itself in the further course. In addition to external events, the chromosomes are also responsible for the development of skills and behavior. In addition, they can transmit existing diseases to the newborn. On the other hand, acquired characteristics, such as a large muscle mass, are not inherited.

Only the 23rd chromosome plays a role in sex, the so-called gonosome. The sex chromosomes are divided into X and Y chromosomes. Females have two X chromosomes, males have one X and one Y chromosome. Accordingly, the sperm ultimately decides which sex is inherited, because women only have X chromosomes and therefore cannot pass on a Y chromosome.

Ailments & Diseases

Without the chromosomes, inheritance could not take place either. Accordingly, great complications can arise if the number or form is not correct.Down syndrome , also known as trisomy 21 in specialist circles, is particularly well known . The name already provides information about the problem at hand: the 21st chromosome exists 3 times instead of twice. Affected children show developmental disorders, but also physical complaints, such as heart defects.

Turner syndrome , on the other hand, is missing a chromosome. The disease can only affect girls because the missing chromosome is the second X chromosome. Patients report short stature and infertility . What is striking about chromosome disorders is that damage to one of the gonosomes can be compensated for in women who have two X chromosomes.

However, this is not the case for men. The fact can be explained by the fact that men only have one X chromosome, which means that defects in it cannot be compensated for. This results in hereditary diseases that almost exclusively affect men. Examples of this are red-green disease , hemophilia or Duchenne muscular dystrophy. In very few cases, the patients are women.

In general, defects in chromosomes can occur during cell division, the fusion of egg and sperm cells or the formation of germ cells. Such a process results in having too many or too few chromosomes. It is also possible that the structure of the chromatids is damaged. In addition, it cannot be ruled out that certain external influences have a negative effect on the chromosomes. These include, for example, radiation or some chemicals.

Diseases that are based on a defect in the chromosomes cannot be treated. It is only possible to mitigate the resulting consequences.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.